Well, the answer is 32.
If they give shell#; then you always have n^2 orbitals. Since it's 4th shell we have total of (4)^2 = 16 orbitals
Now, each orbital has 2 electrons so 16*2 = 32 electrons..
yep, it's 32.
use 2n^2 to figure the number of electrons for each shell.
To explain why 2n^2 works, we gotta understand the quantum numbers.
s subshell (l=0) has 2 electrons (starts at n=1)
p subshell (l=1) has 6 electrons (starts at n=2)
d subshell (l=2) has 10 electrons (starts at n=3)
f subshell (l=3) has 14 electrons (starts at n=4)
Since it's n=4, then possible values for l are 0,1,2,3
to break it down, so you can understand why, look at the periodic table, in the fourth period you're gonna have s,p,d, and f orbitals.
the max amount of electrons that can occupy each subshell is:
s=2 e
p=6 e
d=10 e
f=14 e
EDIT: wow. 3 people just posted the same thing at the same time lol